Merge pull request #1 from alexrudy/feature/breadcrumb

Adds breadcrumb extension

src/bootlace/breadcrumbs.py

@@ -0,0 +1,249 @@
+from collections.abc import Callable
+from collections.abc import Iterator
+from collections.abc import Mapping
+from typing import Any
+from typing import Protocol
+from typing import TypeVar
+
+import attrs
+from dominate import tags
+from dominate.util import text
+from flask import Blueprint
+from flask import current_app
+from flask import Flask
+from flask import request
+from flask import url_for
+from werkzeug.local import LocalProxy
+
+from .util import as_tag
+from .util import is_active_endpoint
+
+
+class Named(Protocol):
+
+    __name__: str
+
+
+V = TypeVar("V", bound=Named)
+
+EXTENSION_KEY: str = "bootlace.breadcrumbs"
+DIVIDER_SETTING: str = "BOOTLACE_BREADCRUMBS_DIVIDER"
+
+
+def endpoint_name(instance: object, attribute: attrs.Attribute, value: str) -> None:
+    if "." in value:
+        raise ValueError("Endpoint names cannot contain dots")
+
+
+@attrs.define(frozen=True, init=False)
+class KeywordArguments(Mapping[str, Any]):
+
+    _arguments: frozenset[tuple[str, Any]]
+
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        arguments = frozenset(dict(*args, **kwargs).items())
+        object.__setattr__(self, "_arguments", arguments)
+
+    def as_dict(self) -> dict[str, Any]:
+        return dict(self._arguments)
+
+    def __getitem__(self, __key: str) -> Any:
+        return self.as_dict()[__key]
+
+    def __iter__(self) -> Iterator[str]:
+        return iter((key for key, _ in self._arguments))
+
+    def __len__(self) -> int:
+        return len(self._arguments)
+
+    def __repr__(self) -> str:
+        return f"KeywordArguments({self.as_dict()!r})"
+
+
+@attrs.define(frozen=True, repr=False)
+class Endpoint:
+    """An endpoint for a breadcrumb, as captured at registration"""
+
+    context: None | Blueprint
+    name: str = attrs.field(validator=endpoint_name)
+    url_kwargs: KeywordArguments = attrs.field(factory=lambda: KeywordArguments(), converter=KeywordArguments)
+    ignore_query: bool = True
+
+    @property
+    def url(self) -> str:
+
+        if isinstance(self.context, Blueprint):
+            name = f"{self.context.name}.{self.name}"
+            return url_for(name, **self.url_kwargs)
+
+        return url_for(self.name, **self.url_kwargs)
+
+    @property
+    def active(self) -> bool:
+        return is_active_endpoint(self.name, self.url_kwargs, self.ignore_query)
+
+    def __repr__(self) -> str:
+        parts = []
+        if self.context is not None:
+            parts.append(f"{self.context.name:s}.{self.name:s}")
+        else:
+            parts.append(f"{self.name:s}")
+
+        if self.url_kwargs:
+            parts.append(f", {self.url_kwargs!r}")
+
+        if not self.ignore_query:
+            parts.append(", ignore_query=False")
+
+        statement = ", ".join(parts)
+        return f"Endpoint({statement})"
+
+
+@attrs.define
+class Breadcrumb:
+    """A single breadcrumb"""
+
+    title: str
+    link: Endpoint
+
+    @property
+    def active(self) -> bool:
+        return self.link.active
+
+    @property
+    def url(self) -> str:
+        return self.link.url
+
+    def __tag__(self) -> tags.html_tag:
+        if self.active:
+            return text(self.title)
+
+        return tags.a(self.title, href=self.url)
+
+
+@attrs.define
+class Breadcrumbs:
+    """The trail of breadcrumbs"""
+
+    crumbs: list[Breadcrumb] = attrs.field(factory=list)
+    divider: str = attrs.field(default=">")
+
+    def __iter__(self) -> Iterator[Breadcrumb]:
+        return iter(self.crumbs)
+
+    def __len__(self) -> int:
+        return len(self.crumbs)
+
+    def __getitem__(self, index: int) -> Breadcrumb:
+        return self.crumbs[index]
+
+    def push(self, crumb: Breadcrumb) -> None:
+        self.crumbs.insert(0, crumb)
+
+    def __tag__(self) -> tags.html_tag:
+        if not self.crumbs:
+            return text("")
+
+        nav = tags.nav(aria_label="breadcrumb")
+        if self.divider != "/":
+            nav["style"] = f"--breadcrumb-divider: '{self.divider:s}';"  # noqa: B907
+
+        ol = tags.ol(cls="breadcrumb")
+        for crumb in self:
+            item = tags.li(as_tag(crumb), cls="breadcrumb-item")
+            if crumb.active:
+                item["aria-current"] = "page"
+                item.classes.add("active")
+            ol.add(item)
+        nav.add(ol)
+        return nav
+
+
+@attrs.define
+class BreadcrumbEntry:
+    """A single entry in the breadcrumbs datastructure"""
+
+    title: str
+    parent: Endpoint | None
+
+
+@attrs.define(init=False)
+class BreadcrumbExtension:
+    """An extension for breadcrumbs"""
+
+    tree: dict[Endpoint, BreadcrumbEntry] = attrs.field(factory=dict)
+
+    def __init__(self, app: Flask | None = None) -> None:
+        self.tree = {}
+        if app is not None:
+            self.init_app(app)
+
+    def init_app(self, app: Flask) -> None:
+        app.config.setdefault(DIVIDER_SETTING, ">")
+        app.extensions[EXTENSION_KEY] = self
+
+    def register(
+        self, context: Flask | Blueprint | None, parent: str | Endpoint | None, title: str
+    ) -> Callable[[V], V]:
+        if isinstance(context, Flask):
+            context = None
+
+        parent_link: Endpoint | None = None
+        if isinstance(parent, str):
+            if parent.startswith("."):
+                if context is None:
+                    raise ValueError("Cannot use relative endpoint without a context")
+                parent_link = Endpoint(name=parent.lstrip("."), context=context)
+            else:
+                parent_link = Endpoint(name=parent, context=None)
+        else:
+            parent_link = parent
+
+        def decorator(view: V) -> V:
+            nonlocal parent_link
+            link = Endpoint(name=view.__name__, context=context)
+
+            if link == parent_link:
+                raise ValueError("A breadcrumb cannot be its own parent")
+
+            self.tree[link] = BreadcrumbEntry(title=title, parent=parent_link)
+            return view
+
+        return decorator
+
+    @property
+    def divider(self) -> str:
+        return current_app.config[DIVIDER_SETTING]
+
+    def _current_context(self) -> Blueprint | None:
+        if request.blueprint:
+            return current_app.blueprints[request.blueprint]  # type: ignore
+        return None
+
+    def _current_endpoint(self) -> Endpoint | None:
+        context = self._current_context()
+        if not request.endpoint:  # pragma: no cover
+            return None
+
+        name = request.endpoint.split(".")[-1]
+
+        return Endpoint(name=name, context=context)
+
+    def get(self) -> Breadcrumbs:
+        endpoint = self._current_endpoint()
+        crumbs = Breadcrumbs(divider=self.divider)
+        if not endpoint:  # pragma: no cover
+            return crumbs
+
+        current = self.tree.get(endpoint)
+        while current:
+            crumbs.push(Breadcrumb(title=current.title, link=endpoint))
+            if not current.parent:
+                break
+            endpoint = current.parent
+            current = self.tree.get(endpoint)
+
+        return crumbs
+
+
+breadcrumbs: BreadcrumbExtension = LocalProxy(lambda: current_app.extensions[EXTENSION_KEY])  # type: ignore

src/bootlace/links.py

@@ -3,10 +3,10 @@
 
 import attrs
 from dominate import tags
-from flask import request
 from flask import url_for
 
 from .util import as_tag
+from .util import is_active_endpoint
 from .util import MaybeTaggable
 
 
@@ -51,17 +51,4 @@ def url(self) -> str:
 
     @property
     def active(self) -> bool:
-        if request.endpoint != self.endpoint:
-            return False
-
-        if request.url_rule is None:  # pragma: no cover
-            return False
-
-        rule_url = request.url_rule.build(self.url_kwargs, append_unknown=not self.ignore_query)
-
-        if rule_url is None:  # pragma: no cover
-            return False
-
-        _, url = rule_url
-
-        return url == request.path
+        return is_active_endpoint(self.endpoint, self.url_kwargs, self.ignore_query)

src/bootlace/util.py

@@ -5,13 +5,16 @@
 from collections.abc import Callable
 from collections.abc import Iterable
 from collections.abc import Iterator
+from collections.abc import Mapping
+from typing import Any
 from typing import Protocol
 from typing import TypeVar
 
 import attrs
 from dominate import tags
 from dominate.util import container
 from dominate.util import text
+from flask import request
 
 T = TypeVar("T")
 
@@ -114,3 +117,21 @@ def converter(value: str | T) -> T:
         return value
 
     return converter
+
+
+def is_active_endpoint(endpoint: str, url_kwargs: Mapping[str, Any], ignore_query: bool = True) -> bool:
+    """Check if the current request is for the given endpoint and URL kwargs"""
+    if request.endpoint != endpoint:
+        return False
+
+    if request.url_rule is None:  # pragma: no cover
+        return False
+
+    rule_url = request.url_rule.build(url_kwargs, append_unknown=not ignore_query)
+
+    if rule_url is None:  # pragma: no cover
+        return False
+
+    _, url = rule_url
+
+    return url == request.path

tests/conftest.py

@@ -7,8 +7,11 @@ def app() -> Flask:
     app = Flask(__name__)
     app.config.update({"ENV": "test", "TESTING": True})
 
+    return app
+
+
+@pytest.fixture
+def homepage(app: Flask) -> None:
     @app.route("/")
     def index() -> str:
         return "Hello, World!"
-
-    return app

tests/nav/test_elements.py

@@ -1,3 +1,4 @@
+import pytest
 from flask import Flask
 
 from bootlace.nav import elements
@@ -14,6 +15,7 @@ def test_link() -> None:
     assert link_e.url == "#"
 
 
+@pytest.mark.usefixtures("homepage")
 def test_view(app: Flask) -> None:
     view_e = elements.Link.with_view(endpoint="index", text="View")
 

tests/nav/test_render.py

@@ -71,6 +71,7 @@ def test_nav_style(style: NavStyle) -> None:
     assert_same_html(expected_html=expected, actual_html=str(source))
 
 
+@pytest.mark.usefixtures("homepage")
 def test_nav_active_endpoint(app: Flask) -> None:
     nav = elements.Nav()
     nav.items.append(CurrentLink(link=View(text="Active", endpoint="index")))

tests/table/test_columns.py

@@ -1,6 +1,7 @@
 import datetime as dt
 
 import attrs
+import pytest
 from flask import Flask
 
 from bootlace.icon import Icon
@@ -23,6 +24,7 @@ class Item:
     when: dt.datetime = dt.datetime(2021, 1, 1, 12, 18, 5)
 
 
+@pytest.mark.usefixtures("homepage")
 def test_edit_column(app: Flask) -> None:
 
     col = EditColumn(heading="Edit", attribute="editor", endpoint="index")